Case-shift mechanism for typewriters and like machines



' April 13, 1954 w. F. HELMOND CASE-SHIFT MECHANISM FOR TYPEWRITERS AND LIKE MACHINES 2 Sheets-Sheet 1 Filed Oct. 25, 1951 INVENTOR- W/LL/AM l. HELMOND BY 2% WM ATTORNEY April 13, 1954 w. F. HELMOND CASE-SHIFT MECHANISM FORTYPEWRITERS AND LIKE MACHINES Filed Oct. 25, 1951 i 2 Sheets-Sheet 2 0 w M 0 TL N NW R E m W 1/ m [M a A M L W W M HL a w fi Patented Apr. 13, 1954 CASE-SHIFT MECHANISM FOR TYPE- WRIT ERS AND LIKE MACHINES William F. Hehnond, Clinton, Conn assignor to Underwood Corporation, New York, N. Y;., a

corporation of Delaware annlit fiqr 9min! 2 195;, erial Na 25 3,11 5 Claims. (01. on-74 This invention relates to case-shift mechanisms for typewriters and like machines, and more particularly to such mechanisms wherein the case-shift body is locked in the normal or lower-case position,the locking means is released by initial depression of the shift key, and the full depressionoi the key completes the ease shift.

An object ,of the invention is to provide an improved case-shift mechanism of this kind in which the manual shifting operation is effected by an easy key depression of substantially constant or unchanging load throughout its operatne str s- Another object of the invention is P provide an improved ease-shift mechanism wherein the twofold function of the shift key, to first release the locking device and thereafter effect the actual case shift, may be efiected without any percaptible change in the resistanee imparted to the key during the transition of the mechanism from the one function to the other.

In its more specific aspect the invention provides a case-shift mechanism wherein the unlocking of the case-shift body andthe shifting of the same to upper case is effected by means clu in a leve his h f rum bo o point in its action of releasing the locking device and on completing said release, to take on the actual shifting, assumes a different fulcrum point, with the end result that operating the shift mechanism entails an even and constant key pressure, and a smooth operation of the s t ke is d- Other objects will be in part obvious and in part particularly pointed out as the following description of a preferred embodiment of the invention proceeds.

In the drawings:

Figure 1 is a perspective view of theprincipal portions of a typewriter involved in case shifting and illustrates the case-shift mechanism embodying the invention in the normal or lowerfifi pos on,

Figure 2 s a s ct nal isi e v t n f th typewriter mechanisms shown in Figure 1, the aseeshift mechanism however, being initially operated to effect release of the locking device,

Fi u 3. i View Si ila in F gi re b s w n th c sshii me ha ism fu O e ated t t is i u pe -case positio an F gur s is a frag ntar view s mi ar t Fi a 13 i wh c in? cas -em t venetian i bein rected brine hi t l ck k y, a the nstan 9' locking an ust p im t r easin sa d ey- The typewriter forming the illustrated embodimer t ofthe invention is of the segment shift kind, although the improved case-shift mechanism is not confined to segment-shift machines. Accordingly, the case-shift member in this instance is a typebar segmentframe I and the parts carried thereby, whereas in platen shift typewriters the caseshift member may be the platen roll or the paper carriage and platen, examples of which are well known in the art.

Referring to Figure 1, the type-bar segment frame 1 carries a segment 8 on which a set of type bars is pivoted in the well known manner, a medial type bar 9 of which is shown. Eaeh type bar, when actuatedby the usual type action, not shown, is adapted to strike at a comi-non printing point on a platen I l, Figure 2, guided by the usual type guide ll supported on the segment 8. Two posts l2 extend forwardly from the segment frarne I for supporting a typehar rest thereon, not shown. Thus, on shifting the segment frame "I, the entire unit known as the type-bar basket is shifted therewith.

? The type head of each type bar 9 has an r pper-case type and a lower-case type, in those relative positions on the type bar when it is in typing position. In segment-shift typewriters when the machine is in' lower case, the normal or unshifted condition, the segment is in its upper positionyFigureZ, from which it is shifted down for typing in upper case, Figure 3.

The segment frame 1 is guided for caseeshift movement at its upper region by a usual balland-race-way unit at each end of the segment frame, of which unit only the raceways M on said frame are shown, the ,complemental raceways -t-hat are not shown heingmounted on the mainframeof the typewriter. vAt its lower region the segment frame *I is guided for movement by arocliable bail l5 pivoted at each end on the typewriter mainframe .and having arms l6 and l pivotally connected to the segment frame I at each end thereof.

A stud, not shown, by which the bail arm I! is pivoted to the segment frame 1, extends beyond said arm to provide a bearing on which a stop block I8 is rotatably mounted. To accurately determine each case position of the segment frame I, the block l8 engages upper and lower stops -2 0 and 2! carried on a side member -22 of theltypewrite r mainframe. The construction and arrangement of the case-shift stop devicejust described forms part of the subjectmatter of' the patentw Helmond, No. 2,349,723, to which reference may be had also for a more'de tailed description of the segment frame guide means as well as the stop device. The segment frame 1 is yieldably held in its normal, upper position, as determined by the block 18 engaged with stop 20, by two suspension springs 23 arranged in th well knownmanner. In effect the springs 23 act as a counterbalance, suspending the entire weight of the type-bar basket assembly in upper position.

The segment frame 7 is blocked in its normal upper position by means including twolocking elements or arms 25 fixed to a common shaft 2% suitably journalled in the mainframe. Each arm 25 has a shoulder 27 at its upper end which enages under a roller 28 rotatably mounted adjacent each end of the segment frame l. Each arm 25 also has a rubber-bound abutment 29 engageable with the roller 28 to determine the normal or locking position of each arm 25. As shown in Figure '1, the shaft 25 at its rightward end extends beyond the adjacent arm 25 and has a stop arm 36 secured thereto, the free end of Which has alug adapted to engage a stud 3| on the mainframe side plate 22. To cushion the impact of arm 38 therewith, the stud 3| has a sleeve of rubber or other resilient material. A spring 32, attached to an upwardly extending portion of arm 30, urges the shaft 26 to rock in a clockwise direction, as viewed in Figure 1, thus tending to swing the locking arms 25 to their locking positions. The lug on stop arm 3!) in engagement with stud 3| determines the unlocked position of the locking arms 25, as shown in Figure 2.

The mechanism for causin the locking arms 25 to release or unblock thesegnient frame '1 and for thereafter shifting said frame to its lower position for upper-case typing will nowbe described. Two shift key levers 33 and their keys 34, one at each side of the typewriter keyboard, are each secured to a rockshaft 35 pivoted at each endto the mainframe. Adjacent the rightward key lever 33, and secured to rockshaft 35 is a lever .arm 36 which in efiect is a part of a composite lever including either key lever 33 and fulcruming on the axis of shaft 35., The lever arm 36 extends rearwardly and carries a lug 3i engage- .able with a stud 38 on the mainframe side member 22 to limit the extentof the downward or operating strokeof the key levers 33. The stud 38 has a sleeve of rubber or other resilient material to cushion the impact of lug 3f therewith.

At a point 39 thereon, the lever arm 36 is flexibly connected to a floating lever 40. Intermediate the ends of lever 45, at a pivot point 4| thereon, lever 4!] is connected by a link 42 to a crank arm 43 secured to the shaft 26 on which the locking arms 25 are secured. At the forward end of the floating lever 45 is a pivot point 44 by which said lever is connected to a yieldable link 45 which in turn is flexibly connected at its upper end to the segment frame 1 by means of the mentioned stud by which the bail arm-H is connected to saidfraine.

The yieldable link, 45 may be of the usual construction comprising two overlapping sections 45 and 41 arranged to slide limitedly relative to each other by two stud-and-slot connections igand urged to a contracted or minimum length of the composite link by a tension spring 49 connected at each end'to the respective link sections 45,

47. As shown in Figure l, the stud of the upper connection 48 is bottomed in its slot and thus determines the normal or contracted-length of .link 45.

The operation of the mechanism for releasing 4 the locking of the segment frame I and then shifting said frame will now be described. As later described, a shift-lock mechanism operable by a key lever 5| for effecting a sustained case shift is provided. However, in that the manual operation of the shift-lcck-key lever 5| becomes effective by transmitting its movement to the shift-key lever 33, it will suffice, in the description of operation, to consider the operation as being eifected only by the key lever 33. Operation by key lever 5| is the same except that a latchin device associated with said lever becomes effective incidental to its operation.

The case-shift mechanism in its normal'or lower-case position is in the condition shown in Figure 1, wherein, as before described, th segment frame I is locked in upper position by the arms engaged with the rollers 28 on said frame. As before mentioned, initial depression of the shift-key lever 33 causes the locking arms 25 to release the segment frame, by moving said arms to "the position shown in Figure 2. As man- 7 ual pressure is applied to the key 34, the counterclockwise rocking of shaft swings lever arm 38 therewith and thus raises the pivotpoint 39 by which said arm is connected to the floating lever 44. This tends to rock lever about either the pivot point 4| or the pivot point 44, depending upon which of the two points imparts the greater resistance to movement from their positions as shown in Figure 1. It will be noted that as the point 39 is urged upwardly, the lever 4i? will tend to fulcrum on point 4| and thus tend to pull point 44 down. Simultaneously lever will tend to fulcrum on point 44 and thus tend to move point 4| up. It will also be observed that,-disregarding the locking effect of arms 25, the resistance to downward movement of point 44 is afforded by the segment-frame suspension springs 23, and that resistance to upward movement of point 4| is imparted by the segmentframe lock spring 32. In order to precede the actual shifting of the segment frame, it is of course necessary that the unlocking of the frame occur in the initial phase of case-shift operation. -To-accomplish this, the "force exerted by sprin 32 resisting -upward movement of point 4| should be less than th force exerted by the springs 23 resisting downward movement of point 44, so that during this initial phase of case-shift operation only the spring 32 will relax and the springs 23 will maintain the segment frame 1 in its normal, upper position.

It should also benoted that in so far as the non-sustained case-shift operation is concerned, the yieldable link 45 may be regarded as nonyielding. That is, its spring 49 is stronger in effect than either the springs 23 or the spring 32 and will only yield under the conditions later described in conjunction with the operation of the shift-lock mechanism for a sustained case shift. a

In that during this initial operation the springs 23 dominate and therefore maintain the segment frame I in the normal position, it follows that the point 44, at which the link 45 connects the segment frame to the floating lever 46, remains stationary. Therefore, as the point 39 of lever 4i) is raised the point 44 acts as the fulcrum about which said lever now swings. This imparts an upward movement to the intermediate point 4| on said levenwhich motion is transmitted through link42. toarm 43 on shaft 25,

causing 1 said .shaft to I rock counterclockwise against the tension of spring 32. As manual pressureon the shift key 34 continues, the lug on arm 3|] is brought into engagement with the stud 3|. This arrest-s rotation of shaft 26 and thus concludes the initial phase of operation of the case-shift mechanism, during which the locking arm '25 have been swung to'the position shown in Figure 2, and the segment frame -'I has remained stationary.

By arresting the said rotation of shaft 26, as described, the swinging of the arm 43 thereon is stopped and this in turn arrests the motion of link 42 which therefore causes the pivot point 41 of said link to the floatin lever 40 to become fixed. Under this condition'the second phase of the case-shift operation begins, the same being distinguished from the first phase in that intermediate point ll of lever M] is now stationary. Being stationary, the point nowbecomes the fulcrum point of lever 50, the fulcrum thus changing from the point 44 to the point 4|. Under this condition further manual pressure on the key 34, beyoncl'th'e initial operating phase,- continues to raise the point tii about theaxis of the shaft 35 and thus further actuates the floating lever E8. Said lever, being now fulcrumed at the intermediatepoint 4i,cau-ses the point 44 to move downwardly, thereby pullin on link 45. This in turn pulls the segment frame 7 down, against the tension of the springs 23, until said segment frame is arrested by the block 18 engaging the stop 2!. This concludes the'second phase of case-shift operation.

In the foregoing description of operation, the initial phase of operation is said to precede the second phase, to accomplish which, the resistance of spring 32 to upward movement of point M of lever to is to be less than the resistance of springs 23 to downward movement of point 44 of said lever. Actually, in view of the normal locking of the segment frame i by the arms 25, the relative force of the two spring means, respectively, on the two points may be substantially equal. By such arrangement, on depressin the shift key, the force exerted on point 39 of lever ill will tend to move both points 4! "and 44 simultaneously. Eowever, since point 44 cannot move until the locking arms 25 become disengaged, the first phase of operation is bound to precede somewhat the actual shifting of the segment frame, which is thedescribed second phase. Of course, as a pull on link i5 is exerted during this first phase, tending to lower the segment frame, it will cause the rollers 28 to press against the upper end shoulders 21 of arms 25. Although this will impose a thrust on said arms, tending to retard their swing to released position, the ability of the rollers 28 to rotate will minimize this retarding effect and allow the arms 25 to move fairly freely from under said rollers. In this way the actual lowering of the segment frame '2 may be directly controlled by the unlocking movement of the arms 25 as the pull on link 45 increases incidental to the further tensioning of spring 32 durin the arm-unlocking action.

Regarding the operating advantages of the improved case-shift mechanism, it may be again noted that the transition from the initial, segment-unlocking phase to the actual segmentshifting phase of the case-shift operation is effected in part by causing a change in the fulcrum point of the floating lever 40. In that the lever 45 is the same operating member in both phases of operation, the transition from one phase to the other is not perceptible to the operator in depressingthe shiftkey. Of some advantage in this regard is the cushioning of the impact of arm 30 with the stud 31 by the rubber sleeve on the latter. This softens the action of stopping the movement of pivot point 4|, which concludes the first phase, and thus conceals from the touch of the shift key that a change is occurring. Another factor assuring a smooth transition from one phase to the other is to have the resistance to the depression of the shift key afforded by the respective spring means 32 and 23 substantially equal so that the typist will not be able to notice any change when the first operating phase is concluded and the second phase begins. In determining the relative strength of the two spring means 32 and 23, respectively, as measured by the resistance to shift-key depression, the changed leverage system, as effected particularly by the change in the fulcrum of lever 33, should be taken into account. In other words, it should be noted that in the action of the spring '32 in resisting key depression, the floating lever ill is acting as a lover of the second order, whereas,-in the action of the spring means 23 in resisting shift-key depression, the lever 46 is acting as a lever of the first order.

The case-shift mechanism may also be operated for a sustained case shift by a shift look mechanism including the shift-lockkey lever :51 and its key 52. Referring to Figure 2, the shiftlock-key lever 5! is pivoted at E3 on the shif-tekey lever 33 and is yieldaoly held in its normal, upper position on lever 33 by a spring 54 tensioned between the two lovers, said normal position being determined by a lug 55 on lever 5i and engaging lever The downward swing of lever 51, against the tension of spring 54, is limited by a lug 55 thereon coming into engagement with lever 33. A latch pawl 51 is pivoted on lever 33 and is urged by a spring 58 to swing clockwise. Latch pawl 5'! has a heel 50 which engages and cooperates with the lug 55 so that in the. normal position of lever 56 :on lever 33, latch pawl 5'! is held in a leftward position. In this leftward position the upper end of pawl 5? remains clear of a latch plate El adjustably mounted on a comb bar 62 at the front of the typewriter, whenthe shift key 34 is operated, as demonstrated in Fig ure 3. However, when the shift-lock 'keytal is depressed, the limited downward swing of lever 51 on lever 33 lowers the lug 55 and said lug, in receding from the heel Bil of latch pawl 5 allows said pawl to be swung rightwardly by its spring 58, see Figure 4. This allows pawl 51 to swing toward the latch plate 6! so that, at the full ole pression of the shift-key lever 33 by the lug 56 upon continued pressure on key 52, the pawl '51 will snap under said latch plate. The force of spring 54 is greater than the force of spring 58, so that, upon release of finger pressure on key 52, spring 54 acting on lcey lever 5|, allows 111$ 55 to re-engage pawl heel 53, thus tending to unlatch the pawl. However, the force of springs 23 tending to return the key levers 33 is greater than the force of spring 5t, and therefore the key levers 33 will rise ahead of key lever -5l. The release of key 52 has allowed the shift-key lever 33 to rise and this in turn raises pawl ii] bodily and presses its end shoulder against the bottom edge of latch-platet l. 'By this frictional engagement, pawl 51 is maintained in the latched position despite the tendency of the lug 55 to disengage the latch. In this way the pawl 51 is held in latched position, due to the endwise pressure exerted upon it by the shift lever 33. It fol- 7 lows that a slight downward swing of shift-key lever 33 will remove said pressure and thereby free the latch pawl 51 to swing leftward, the heel 60 thus rising and allowing shift-lock lever to assume its normal, raised position on lever 33.

,It may be here noted that the case-shifted position of the segment frame 1 is exactly determined by the engagement of stop block it with the lower stop 21, as demonstrated in Figure 3,

However, in order that the frictional latching of pawl 51 may function as above described and, in order that the release of said pawl may be effected by pressing the shift key 34, it is necessary that the shift-key lever 33 be depressible slightly beyond the position which it assumes at full case shift. It is to accommodate this further movement that the yieldable character of link 45 is provided. That is, either incidental to effecting a sustained case shift or in releasing the shift lock, the shift-key lever 33 is depressed slightly below the position shown in Figure 3, during which movement the spring 49 of the yieldable link 45 allows said link to stretch, the limit of depressing key lever 33 being fixed by the engagement of the lug 37 on lever arm 36 with the stud 38, as shown in Figure 4.

Having thus described the invention, what is claimed is:

1. In a typewriter, a member case-shiftable from a normal to a shifted position and tending to maintain its normal position, locking means normally effective to lock said case-shiftable member in normal position and including a rockable arm adapted upon being actuated to cause said locking means to release said member, and mechanism for actuating the rockable arm to release said case-shiftable member and for shifting said member to the case-shifted position, said mechanism including a floating lever, key-controlled means operatively connected to one end of said floating lever for rocking said lever, an operative pivotal connection from the other end of said floating lever to said case-shiftable member, and a second operative pivotal connection from an intermediate point on said floating lever to the rockable arm of said locking means, said floating lever in operation being rockable about one or the other of said pivotal connections.

2. In a typewriter, a member case-shiftable from a normal to a shifted position, means tending to maintain said member in its normal position, a swingable locking element spring-urged to a position in which it engages and locks said case-shiftable member in normal position, and mechanism for swinging said locking element out of locking engagement with the case-shiftable member and for shifting said member to the caseshifted position, said mechanism including a floating lever, key-controlled means operatively connected to one end of said floating lever for actuating said lever, a link connecting the other end of said lever to said case-shiftable member, and an operative connection from an intermediate point on said floating lever to said locking element.

3. In a typewriter, a member case-shiftable from a normal to a shifted position, means tending to maintain said member in its normal position, a swingable locking element spring-urged to a position in which it engages and locks said case-shiftable member in normal position, and mechanism for swinging said locking element out of locking engagement with the case-shiftable member and for shifting said member to the case-shifted position, said mechanism including a crank arm adapted to swing said locking element, means to limit the swing of said locking element to a degree ample to unlock the caseshiftable member, a floating lever, key-operable means operatively connected to one end of said floating lever for actuating said lever, a link connecting the other end of said lever to said case-shiftable member, and a second link connecting an intermediate point of said lever to said crank arm.

4. In. a typewriter, a type-bar segment frame case-shiftable from a normal upper position to a lower case-shifted position, spring means yieldably holding said segment frame in its normal upper position, a swingable locking element spring-urged to a normal position blocking shifting of said segment frame from its upper position, a crank arm adapted to swing said locking element, means to limit the swing of said locking element to a position unblocking the segment frame, a floating lever operatively connected at one end to said segment frame, an operative connection from an intermediate point of said floating lever to said crank arm, and key-operable means operatively connected to the end of said floating lever opposite said segment-frameconnected end, whereby upon actuating said key the locking element is swung to unblocking position and the segment frame is case shifted to lower position.

5. In a typewriter, a type-bar segment frame case-shiftable from a normal upper position to a lower case-shifted position, spring means yieldably holding said segment frame in its normal upper position, locking arms having their upper ends engaging said segment frame to block said frame against shifting from its normal upper position, a rockshaft mounting said locking arms for swinging movement to unblock the segment frame, a second spring means urging said looking arms to segment-frame-blooking position, a crank arm for rocking said shaft against the force of said second spring means, means to limit the rocking movement of said shaft to an extent to bring the locking arms clear of the segment frame, a floating lever, means including a shift key operatively connected to one end of said floating lever for actuating same, a link connecting the other end of said lever to said segment frame, and a second link connecting an intermediate point of said lever to said crank arm, whereby upon actuating said shift key the locking arms are swung clear of the segment frame and the segment frame is then case shifted to lower position.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,244,729 Handley Oct. 30, 1917 1,479,716 Hess Jan. 1, 1924 1,529,783 Going Mar. 17, 1925 2,306,604 Helmond Dec. 29, 1942 2,501,605 Koca Mar. 21, 1950 

